Friday, January 28, 2011

Is Yellowstone gonna blow? Sure. Will everybody die? Sure, absolutely. But there is pretty much no connection between the first question and the second. Yellowstone caldera will in fact erupt again some day; it's a forty mile wide caldera with a huge magma chamber miles deep in the crust. That's the reason there are geysers there, and all those hot springs. And everyone will die, eventually. That's kind of a rule about living. But worrying about whether I'm gonna die from an eruption at Yellowstone is so far down my list of concerns that I am more worried about being gnawed to death by a pack of angry prairie dogs. It could happen, but it is highly unlikely.I'm writing on the subject because a commenter asked for my take on the news this week about the activity around the Yellowstone caldera (for the record, "supervolcano" isn't a geological term). My best advice, before I finish with my own two cent's worth, is to check out the Eruptions blog here and here. Erik Klemetti does some excellent analysis of the story and how quickly things can be overblown by a media that thrives almost exclusively on spectacle, and has little use for reasoned discussions of the actual risks.

As I considered the question of an 'informed' response, I had to wonder if I'm not guilty of the same sort of exaggeration and sensationalism of cable news and other media. In my pursuit of educating others, I am not above discussing lurid tales of death and geological mayhem. After all, when I talk about volcanoes in class, I lead with Krakatoa, Tambora and Pompei, and I discuss the potential effects of a gigantic rhyolite caldera eruption such as those that took place at Yellowstone three times in the last two million years (not to mention broadly equivalent eruptions at Valles Caldera and Long Valley Caldera). I have a clear conscience on the matter, because I follow up with a discussion of the actual risk and probability of such events happening to our time; an eruption like the Yellowstone Caldera happens somewhere in the world every few hundred thousand years. Smaller, but certainly dangerous eruptions like those of Tambora (1815), Krakatoa (1883) and Katmai (1912) happen somewhere in the world on a scale of decades. And when these events take place there are clear signals that something is about to happen.

So, the Yellowstone Caldera floor rose around a foot during the last decade (that's the caldera in the picture above; I was standing on one rim, the mountains in the far distance form the other rim). There was an intrusion, a sill, that was filling and inflating with magma. There is nothing unusual or particularly alarming about this, as Yellowstone is an active magma chamber, and such events are normal. Although it has been 70,000 years since the last eruption in the park (and more than 600,000 years since the so-called 'supervolcano' eruption), it could happen again, but any activity would be accompanied by many other phenomena that would provide plenty of information about the scale of the eruption and the hazard to people in the region. My take? Learn about Yellowstone; it is a fascinating place, worthy of our attention and worthy of protection as a crown jewel in our national park system. But worry about the end of civilization as we know it in a vast explosion of fire and volcanic ash? No, there are other problems that we need to think about.

The best quote on the matter? From Max Read at Gawker: "But who do you trust, some kind of "professor," or your overactive imagination?" To which I might add: "But what about professors with overactive imaginations?"

OK, I'm not a baker, I'm not a cake-maker, but I can eat with the best of 'em. This month's Accretionary Wedge, hosted by Callan Bentley at Mountain Beltway, is on a delicious topic, food! Educational food, no less...

I hereby challenge my fellow geobloggers (and any newbies who want to participate) to explore the interconnections between geology and food. This can take any form you want, but I’m really hoping for some edible, geologically accurate models. Yummy stuff that illustrates and informs about earth science? Yes, it is possible!

The end of the semester in my historical geology class is usually accompanied by a social gathering, and an interesting cake is usually in the mix. The picture above was a complicated mess befitting of the subject, an ocean-continent convergent boundary, i.e. a subduction zone. The brown is the region of a magmatic arc, where magmas rise to the surface forming a series of andesitic stratovolcanoes (the red glob on the right is the molten rock!). The yellow strip is the forearc basin, a shallow sea where sediments form thick layers. The only piece I can't make out specifically is the accretionary wedge, unless the blue is not ocean water (ironic, given the name of the carnival). I'm not sure how to interpret the rest of the layers, but I can report that they were tasty!

Edible education took a different turn a number of years ago when I had the chance to see Walcott's Burgess Shale quarry in British Columbia (one of my very first blogs was on the subject). The site is considered to be one of the most important fossil discoveries in the world as it yields up thousands upon thousands of soft-bodied Cambrian animals. This is important because usually only hard-shelled creatures are ever preserved. The Burgess fauna gives us a glimpse of the complete ecosystem that existed at the "dawn" of complex life around 510-515 million years ago.

As one might expect, the quarry is carefully protected, and collecting could actually land you in jail. So we thought it interesting that our guide promised that we would all get a trilobite of our own if we survived the six-mile hike to the quarry. The "trilobites" are below!

Monday, January 24, 2011

So what was Geotripper doing providing advice on human relationships on a geology blog yesterday? Randy got it exactly right, I was teaching chemistry! Haven't you ever wondered what holds the world together, how a bunch of supermicroscopic atoms can stick to one another and form such beautiful rocks and minerals? A great many people might be interested in knowing, but feel intimidated by the level of knowledge seemingly required to understand such things. To understand a crystal, one needs to know of protons, electrons, neutrons, elements, and bonding. To fully understand an earthquake or a tsunami one needs some basic understanding of the behaviour of waves. To understand the twinkling of a star in the sky, one needs some grounding in the nature of the electromagnetic spectrum. It is a tall order, but not impossible. The knowledge is there for anyone to comprehend if they wish to...I will explain the specifics of our Dear Gabby advice at the end of this post.

Geology and the earth sciences occupy a special place in the academic universe. They are the very tangible examples of chemistry and physics at work in the real world. Not the strange world of atoms and smaller objects where Newtonian physics falls apart into strange new rules. Not the vastness of an unimaginably strange Universe. It is the ground beneath our feet, the flooding of a nearby river, the shock of an earthquake, the price of gasoline at the local pump. It is the prediction of next week's snowstorm, the drought of the next decade, and sea level rise in the next century. It is the planning for the end of an oil economy. An understanding of the earth sciences is critical to making the best choices in resource use and allocation in an overpopulated world.

National parks and monuments are not generally established because they preserve some aspect of physics and chemistry. If they don't preserve a historical battleground or unique plant or animal, they are there because something of geology is worthy of our interest and protection. We may photograph the bears, deer and squirrels that inhabit Yosemite, Yellowstone or Grand Canyon, but the meaning of the parks is in the rocks. The squirrels live everywhere, but the geysers, rock strata and gorges make these places unique. Communicating the meaning and value of these parks to society is prime concern of the park's interpretive rangers.

That brings us to the challenge. To be a geology/earth science major, one needs to be a real polymath, a Homo Universalis (look it up! I had to). It is generally recognized that the candidate needs to master calculus, physics and chemistry, usually in classes that has him or her competing directly with actual math, physics and chemistry majors. It is not the easiest major to pursue. In an ideal academic world, the geo-major would have prerequisites in all of these listed fields before ever setting foot in a physical geology course.

This is not feasible or possible in my world of the community college. A prerequisite like that would leave me with three or four students each semester (hmmmm....that's a thought). Our community colleges serve many constituencies and few of my students will actually end up as majors. They will become teachers, nurses, accountants, firefighters, small business owners and so on. They take a geology/earth science class for many reasons, but most often because it is one of the listed physical science lab electives they need for their general education requirements. Our goal is not to produce geologists and earth scientists (although it is nice when that happens), but to produce an informed community of educated citizens.

So, I have the challenge (and privilege) of assisting my students in understanding some basic principles in physics and chemistry without getting bogged down in aspects of the sciences that they won't need in order to understand introductory geology. Chemistry is covered in about 2 hours and 40 minutes. The boiled down version of chemistry that I present would probably appall my colleagues down the hall, but they will have time to fix it when my students take a chemistry course a semester or two later. In the meantime, the students will have more than enough to try and understand; why not make it as memorable as possible?

They tell us we should not anthropomorphise inanimate objects like atoms (atoms don't "want" to do anything or "behave" in a particular way, they just act according to the laws of physics). But that sort of takes the fun out of explaining atomic activity.

So...atoms are in fact couch potatoes, in the sense that they exist and react in such a way as to maintain a stable low energy state. This generally involves having a specific number of electrons in the outer energy shells. They achieve the stable outer shells by giving up or taking in electrons from the local environment, i.e. from or to other nearby atoms. This leaves atoms in an ionized state, meaning they now have a positive or negative charge. The oppositely charged particles are attracted to each other to form an ionic bond.

Other atoms achieve stability by merging their orbiting electron shells and sharing the fast moving particles. Such outer-shell electrons are called valence electrons, and the bond is a covalent bond.

In some minerals like gold, silver or copper, the electrons flow freely throughout the solid and are not tied to any specific atoms, a so-called metallic bond (ever wondered what electricity actually is?).

And as Randy points out, the noble gases already have filled outer electron shells, so they don't react or bond with other atoms at all. These elements include helium and argon gas. A moment of truthfulness here: I was actually thinking of the very weak Van der Waals bonds, but the example of the noble gases works much better as a metaphor of non-commitment!

The next step is to understand how these bonds lead to the formation of the crystals (and crystalline solids) we find scattered throughout the crust of the earth (such as the amethyst quartz above). I love crystals, not for spiritual new age reasons, but for the assurance they provide us that there is order in the Universe. They are beautiful reminders of the accomplishments of atomic couch potatoes seeking that nirvana of the lowest energy state possible.

Dear Gabby...I just don't understand human relationships. I'm lonely, I want to be with other people, but I just don't get it. What can I do??SignedUnfulfilled

Dear Unfulfilled

Humans find their loneliness is ameliorated by love, commitment and bonding. But everyone is different. This is what human togetherness is all about...

It is said that in love, opposites attract. But sometimes one does all the giving, the other all the taking.

In olden days, before "domestic relationships", "living together" and "shacking up", there was once something called "cohabitation".

In the 1960s there was something called "free love", a sort of joyful noncommitted relationship.

But with some, there seems to be a problem with any kind of strong commitment.

Good luck with your search for bonding with others!

Gabby

Dear GabbyPeople have been calling my hubby a "couch potato". I don't get it. What is a couch potato?Signed,Tired of serving

Dear Tired of Serving:

A couch potato is one of those people whose sole ambition is to expend the least energy possible. Think about it. I'll bet that hubby spends his day prone on the Lazyboy Lounger, and exercises by pressing his thumb on the remote, and communicates with the rest of the household by shouting "get me a beer, honey", because he is so darn lazy he can't rise and do it himself. He may only get excited when the television transmits a touchdown, but he soon sinks back down.

I'm sorry, but he will never change. I suggest going to a CPA meeting, Couch Potatoes Anonymous.

Signed,

Gabby

So of course, the dear readers of this blog are saying "what the heck does this have to do with geology, O Geotripper???

Individual maps can be viewed on screen; PDF images and GIS files can be downloaded by selecting a specific quadrangle map. Other CGS online map updates: both the geology and fault activity maps for the state are viewable online as well as the regional 1:250K and 1:100K geologic map series. The older Geologic Atlas series of maps will soon be made available as well. See http://www.consrv.ca.gov/cgs/information/geologic_mapping/Pages/googlemaps.aspx

On a different note, March 20-26, 2011 is National Tsunami Awareness and Preparedness Week. CGS has lots of downloadable educational/outreach materials available at http://www.tsunami.ca.gov/ . Scroll down the main page to see links to both the inundation maps (CGS) as well as the CalEMA MyHazards website. We provide numerous links to K12+ tsunami curriculum and activities. For more information on availability of printed educational materials contact:

Saturday, January 22, 2011

How can you tell it's still winter in Southern California? There are some definite clues in the picture above, though you may have to look closely. I'm not gloating or anything; I live in Central California under some of the most pernicious gloom and cold damp fog imaginable. But I grew up down this way, and I have dreams sometimes of the gorgeous weather. I'm not down here for a happy reason (a funeral for a grandmother), but it's nice to see a beautiful day, and to see some family I haven't seen in a while.

People like to make jokes about the traffic, the floods, the earthquakes, the smog, the urban blight, and all the other stereotypes of SoCal, but there are reasons that 20 million plus people have chosen to live here, and the winters have to be pretty high on the list.

So let's get to the clues. First, you have to look carefully at the tower in the photo above, a little to the right. There's something in the distance behind it. Let's zoom in.... Ah, yes, that's Mt. Baldy, and number one winter clue is, you can actually see it from Balboa, and number two, it's still got snow on top!

Clue number three appears below: there are slightly fewer people actually in the water!

Thursday, January 20, 2011

Silver Fox over at Looking for Detachment has occasionally posted some favorite road songs and something about the idea struck a chord with me (no extra charge for puns). So much of work in the field involves music, whether to keep one company on a long road, or to dispel the darkness beyond camp. It sometimes seems like a primeval urge to chase away the darkness with firelight and chanting (though, since I'm not likely to be eaten by a sabertooth, I embrace the darkness and the starry cosmos too).

I often carry a guitar in the field, and offer my students a sample of songs for the road. I have to admit, they are polite, but don't often know the songs I sing. From somewhere deep in the wells of my past, I've amassed a repertoire of folk songs that are invariably sad, songs about hitting bottom, songs of lost loves, songs of betrayal, and songs of missing home. Townes Van Zandt, for instance, or Gordon Lightfoot.

Even though I'm a long ways from the field, the beauty and healing power of music was driven home for me recently. Sometimes one can't sleep, fretting about one thing or another in a way that keeps one tossing and turning all night. In the light of day, I fired up the computer, and Peter, Paul and Mary popped up with my favorite Gordon Lightfoot song, Early Morning Rain:

In the early morning rain, with a dollar in my handWith an aching in my heart and my pockets full of sandI'm a long way from home, and I miss my loved one soIn the early morning rain with no place to go

Stupid irritating problems lose their significance when we hear the storyteller tell of hitting absolute bottom...

Out on runway number nine, big 707 set to goBut I'm stuck here on the ground where the cold winds blowWell the liquor tasted good and the women were all fastThere she goes my friend, she's rolling now at last

Here the mighty engines roar, see the silver bird on highShe's away and westward bound, high above the clouds she'll flyWhere the early rain don't fall and the sun always shinesShe'll be flying o'er my home in about three hours time

Silver Fox says that airplane songs are not part of the road song genre, but this poor guy is not on the airplane...

This old airport's got me down, it's no earthly use to meCause I'm stuck here on the ground, cold and drunk as I might beYou can't jump a jet plane like you can a freight trainSo I'd best be on my way in the early morning rain

And no resolution, either. I have Gordon Lightfoot's version, and I love it, but the soaring harmonies of Peter, Paul and Mary take the song to a whole different place. Old folk songs touch on deep emotions that we spend a lot of time and effort to avoid feeling.

My other favorite road song also breaks Silver Fox's rule. There is no road, and instead there is no connection at all, just a wide sea. The Water is Wide is hundreds of years old (the old title is Waly, Waly, gin Love be bonny), and many have sung the song, including James Taylor in one nice version. For beauty of voice, I don't think I've heard a nicer version than Niamh Parson's. I listen to it constantly (I wish the video was of her playing the song, though):

The water is wide, I can-not cross o'er.And neither have I the wings to fly.Build me a boat that can carry two,And both shall row, my true love and I.

A ship there is and she sails the seas.She's laden deep, as deep can be;But not so deep as the love I'm inAnd I know not if I sink or swim.

I leaned my back up against a young oakThinking he were a trusty treebut first he bended and then he brokeThus did my love prove false to me.

O love is handsome and love is kindand loves a jewel while it is newbut when its old love it growth coldAnd fades away like the morning dew. I suppose it's not fair to leave the poor homesick students sobbing with misery, but it's also wonderful, in a way, to understand the pain of the singer, and realize that maybe things aren't really all that bad. And if things are that bad, it's good to have company...

Tuesday, January 18, 2011

Andrew Alden over at About.com Geology mentions a skill and privilege that geologists and rock/mineral lovers need to remind themselves they have: Permission to Play! In other words, get out and have some fun looking for stuff. I live in the middle of California, in a place that at first glance does not offer many chances to build a collection of nice specimens of rocks. I thought about this a few years ago when I was trying to help some teachers build collections of classroom specimens of common rocks and minerals. I put together a brief guide to hunting for rocks in Central California. I've reproduced it below in the hope that some of our local rock-lovers will go out and play!

Where to find Rocks and Minerals in and around Stanislaus County

Living in a flat valley as we do, one may be tempted to think that it will require a lot of money and effort to accumulate samples of common rocks and minerals for the classroom or for collections. In actuality, we live near excellent exposures of a large variety of rocks and minerals that could be collected in two or three Saturday trips from the Modesto area.

Volcanic Rocks:

Basalt: Table Mountain lavas are made of a black volcanic rock that looks like basalt (it is actually a rare type of lava called latite). It can be found along Highway 108, especially near Knights Ferry, and Yosemite Junction.

Andesite: Gray volcanic rock that originates in eruptions from mountains like Shasta, Rainier or Fuji. It was erupted from vents around the Sierra Crest from Sonora Pass north around 20 million years ago, and can be found as cobbles in streambeds like the Stanislaus River.

Rhyolite: Light colored or pinkish volcanic rock that is produced by violent eruptions. The Valley Springs Formation can be found in the Sierra Nevada foothills from the Tuolumne River drainage north to, well, Valley Springs. It was once used as building stone in some Gold Rush-era buildings. The light colored cliffs along Highway 132 between Waterford and LaGrange are rhyolite ash deposits. Other exposures are found along the Stanislaus River upstream of Knight’s Ferry.

Obsidian and Pumice: These are both forms of volcanic glass, the first solid and shiny, the second, frothy. Obsidian is not normally found in the region, except as artifacts like arrowheads that were carried into the area. The rocks are found east of the Sierra Nevada in the Mono Craters area, and at Medicine Lake Highland northeast of Mt. Shasta.

Plutonic Rocks:

Granite: Granite is well-known as the rock of the Sierra Nevada, although the rocks found in Yosemite National Park include many types of similar “granitic” rocks such as granodiorite, tonalite, and diorite, and actually not a whole lot of granite! Collecting is not permitted in the national park, but many cobbles of granitic rocks can be found in the Merced River on Highway 140 just outside the park, and in the upper drainages of the Stanislaus River on Highway 108.

Diorite: See above!

Gabbro: The dark plutonic igneous rock is sometimes incorrectly called “Black Granite”. It is relatively rare, but can be found locally in at least two places, in Del Puerto Canyon above Patterson (just beyond the quartz mine), and along Highway 140 between Cathy’s Valley and Mariposa.

Peridotite: This rock comes from deep within the earth, and is quite rare at the surface. It is often altered even when it is exposed. Some relatively unaltered peridotite can be found in the uppermost reaches of Del Puerto Canyon (about three miles beyond Frank Raines Park), and near the site of the old Pinetree Mine at the brink of Hells Hollow on Highway 49 about 12-13 miles north of the town of Mariposa.

Sedimentary Rocks:

Sandstone and Siltstone: The Central Valley is underlain by several miles of layered sediments ranging in age from 140 million years to the most recent floods of our local rivers. Luckily, these layers have been pushed up to form the eastern edge of the Coast Ranges where they can be easily observed. Del Puerto Canyon is an ideal place to find a variety of shale, siltstone, conglomerate and sandstone samples. The layers are exposed in the lower 7-8 miles of the canyon. Fossils are occasionally found, especially in the first two miles of the canyon, where leaves can be discovered with a bit of work. The partial remains of a Hadrosaur dinosaur were found in the 1930’s.

Gypsum, Coal, and Limestone are not common in the area. Vast limestone exposures can be found in the White-Inyo Mountains east of the Sierra Nevada.

Metamorphic Rocks:

Slate and Greenstone: The Sierra Nevada foothills are composed almost entirely of slate and greenstone, the products of heating and deforming oceanic muds and volcanic flows. Individual sites are widespread. Dredge tailings, such as those found between Snelling and Merced Falls on the Merced River, are good places to find cobble-sized samples.

Marble: The Sierra Nevada foothills east of Highway 49 contain a number of excellent exposures of marble. Not surprisingly, the location of caverns is an excellent clue. Columbia, Camp Nine Road, Moaning Caverns, and California Caverns are good places to start.

Quartzite: Though less common than the previous rocks, quartzite is occasionally found in the higher parts of the Sierra foothills. Because it is a very hard and resistant rock, the best place to find samples is in streambeds and dredge piles (Merced and Stanislaus rivers).

Serpentine: The California State Rock! The former mantle rock is found along major faults in the Sierra Nevada foothills along Highway 49, and in the Coast Ranges, especially in the upper part of Del Puerto Canyon, just beyond Frank Raines Park. Two of the best exposures are at the base of Bagby Grade where Highway 49 crosses the Merced River, and just north of the town of San Andreas.

Schist and Gneiss: These are not common in our area. The extreme southern end of the Sierra Nevada near Tehachapi Pass, and the San Gabriel Mountains of southern California have exposures of these rocks. Further afield, Death Valley (no collecting), and several mountain ranges in the vicinity of Las Vegas are other good localities for finding them.

Saturday, January 15, 2011

As sort of a postscript to my previous post on the Glendora Ridge Road, I wanted to mention what's visible to our Other California explorers if they look south from the highway. There is a deep dark valley down there...and it's a forbidden valley.

When I was a young man living in the valley below the San Gabriel Mountains, I studied maps of Angeles National Forest obsessively, and I climbed nearly every named mountain peak in the vicinity (with the prominent exception of Iron Peak, aka Sheep Mountain). But there was a blank spot on the map south of Glendora Ridge Road. It was labeled "San Dimas Experimental Forest - No Entry". And that was it. No explanation. In those pre-internet days, there wasn't much I could do to find out what secret and nefarious experiments were being carried out in that valley. To me, it was sort of a national forest "Area 51". And of course, it seemed so unfair that we couldn't explore the area, with the meadows, waterfalls and creeks that must be hidden in the folds of the valley.

When I returned to the region a few weeks ago after a long absence, I found it was not nearly so hard to find out what the experimental forest was all about (the internet is kind of nice that way). It was originally established in the 1930s to study ways of increasing water yields in the lower canyons. The role of the experimental forest evolved over time to become an important baseline region to study the vegetation, soils, slopes, water, air, and fauna of the chaparral plant communities of Southern California. Most of Angeles National Forest has been developed for a variety of uses (the "multiple-use" conundrum), and there are few areas that have not been severely influenced by human activities. The canyon is truly an open-air laboratory, and although it is not open for recreational use, it isn't that difficult to arrange educational tours, or conduct original research using the lab facilities in the lower canyons (with a database of more than 70 years of measurements and observations) .

The San Dimas Experimental Forest is now part of the Pacific Southwest Research Station, which consists of more than a dozen such areas in California and Hawaii. It is also recognized as a Biosphere Reserve by UNESCO's Man and the Biosphere program. For the mysterious forbidden valley of my youthful days, that's pretty cool! But darnit, where is the UFO landing pad?

OK, not quite as deep as the Grand, but who's to quibble over a few hundred feet? That's what I love about California: it has a lot of famous places that everyone has heard about, places like Yosemite, Death Valley, and Big Sur, but it also has many corners that are known locally perhaps, but are not all that prominent in the public consciousness. They are parts of state parks or national forests, sometimes private lands, and they offer geologic treasures that would be national landmarks in any other setting. That is the theme of my sporadic posts on the Other California, a description of these unheralded places.

The beautiful skyline in the photo above comes from the high point on the Glendora Ridge Road, a paved highway with no picnic areas, no campgrounds, no signed overlooks, and no particular destination or purpose that is obvious. The road connects Baldy Village at the east end of the San Gabriel Mountains with roads rising out of the San Gabriel River and the urban sprawl of the Los Angeles Basin around Glendora and San Dimas. For such an unpublicized road, the Glendora Ridge Road is spectacular. It winds across the top of a high ridge, a fault block caught between the now inactive San Gabriel fault and the highly active Sierra Madre-Cucamonga fault system along the steep mountain front. The rocks include beautiful exposures of Proterozoic gneiss and schist, some of the oldest rocks in California, along with Mesozoic or early Cenozoic granitic rocks (some gneiss is shown in the photo at the end of this post). To the north, the road provides a bird's-eye view of one of Southern California's more dramatic wild areas, the Sheep Mountain Wilderness. It always seemed inconceivable to me that such a place could exist just 10 miles as the crow flies from the urban sprawl of the Los Angeles basin. The wilderness encompasses nearly 8,000 feet of vertical relief from the bottom of the East Fork of the San Gabriel River to the summit of Mt. San Antonio (Mt. Baldy). The canyons are immense, with depths exceeding 4,000 feet in a few places. The rivers (another SoCal rarity) are so rugged that few trails reach them, and at least one of them is a natural trout fishery (Upper Fish Fork). The wilderness is an ideal habitat for the rare Nelson's Bighorn Sheep. I was lucky one year while hiking on the boundary of the wilderness; I chanced upon a herd of a dozen or more. Being who I am, I fumbled in my pack for a camera (one of the old-fashioned kind with this stuff inside called 'film'). They heard the noise and skittered away. I got a great picture of a dust cloud...

Mount San Antonio (10,064 feet) is the highest point in the wilderness. The summit is hidden by clouds in the pictures below, but the mountain is one of the most familiar sights on the Southern California skyline. Thousands of people hike to the summit every year along a trail that starts at the Mt. Baldy ski area. There are two other approaches to the summit, but the number of hikers every year on those routes probably numbers in the dozens. A long and rugged trail approaches from the north part of the wilderness over Dawson Peak and Pine Mountain. Perhaps one of these days my brother will guest-blog about the time we, uh, "misplaced" him on this trail during an Explorer Scout backpack trip...

The other trail to the summit starts at Baldy Village and climbs almost 6,000 feet to the summit. To call this a difficult trail is nearly an understatement, but climbing it was one of the great adventures of my youthful days. Hot and dusty in the lower reaches, and spectacular views the whole way up. It's a good place to catch sight of the bighorn sheep.

There is no official Sheep Peak, by the way. It is the informal name of the prominent peak in the center of the wilderness area, 8,007 foot Iron Mountain (the prominent peak on the right in the picture below). I've never had the privilege, but the climb to the summit is said to be one of the toughest hikes in the south state, with great views and a chance to explore some old gold mines along the way. Glendora Ridge is paved and well-maintained. That it exists is kind of a mystery to me, and I welcome any explanations as to why it was built. According to Russ Leadabrand (a travel author and Sunset Magazine contributor in the 1960s and 70s), the road was constructed in the early 1930s. I have thought of one possible reason. After my comments a few weeks back about the hazards of living in Southern California, especially adjacent to the high mountain ridges, it occurs to me that Baldy Village would have but a single access road if Glendora Ridge Road wasn't there. A single way out in the event of a major earthquake, a major flood, a major fire, or big landslide. The same problem applies to the developments in San Gabriel Canyon off to the west, a highway that also connects with Glendora Ridge. It looks to me like Glendora Ridge Road is the evacuation route... Whether it is or is not the escape route, it is a great road to drive. Unfortunately the local kids with their newly minted driver licenses know about it too, and a Google search on the subject of the road is likely to turn up stories of tragic car crashes as much as anything else (one of my high school buddies survived a 400 foot plunge off the highway). But for us last month it was uncrowded, and with the clear December skies, a beautiful excursion looking towards the high mountains, and the crowded valleys below.

Wednesday, January 12, 2011

Courtesy of Park Geologist Greg Stock, a review of mass wasting events in Yosemite National Park this year....

2010 Rock Fall Year in Review

Although not as newsworthy as those of recent years, many significant rockfalls occurred in Yosemite in 2010. The largest occurred on October 11from the southeast face of El Capitan, midway up the cliff and along thepath of Horsetail Falls. This was actually the largest in a series of rockfalls from that area over several days. There were no associated injuriesdespite the fact that these rock falls occurred during the peak of the fallEl Capitan climbing season. The cumulative volume of these failures wasapproximately 1,700 cubic meters (5,000 tons).

Another area of notable rock fall in 2010 was the Rhombus Wall immediatelynorth of the Ahwahnee Hotel. This area was first active in August of 2009,with subsequent failures in September 2009. Quiet for the early part of2010, the cliff experienced renewed activity beginning in August, with atleast five rock falls radiating outward from the initial failure pointbetween August and November 2010. The cumulative rock fall volume overthis interval was 187 cubic meters (550 tons). This area of the RhombusWall is an impressive example of a progressive failure due to stressredistribution and crack propagation, and presents a unique opportunity tolearn more about this complex process.

Ironically, the most serious rock fall of 2010 was also one of thesmallest. On October 5, 2010, following several days of intense rain,local children Serra Weber, Carmen Ortiz, and Angel Ortiz were playing onthe talus slope near the Church Bowl Picnic Area when a 1.7 cubic meter (5ton) rock fell from low on the cliff. The rock fell directly onto Serra,pinning her and causing life-threatening injuries. Carmen and Angel ran tothe nearby Yosemite Medical Clinic and notified the medical staff, whoresponded immediately. Serra was flown to a local hospital where sheremained for several weeks. Serra recently returned to school in YosemiteValley, where she, Carmen, and Angel were honored for their bravery duringthis event.

Other areas in Yosemite experiencing rock falls in 2010 include thePorcelain Wall (on the western shoulder of Half Dome), Glacier Point,Middle Brother, Middle Cathedral, Indian Canyon, and the Merced RiverGorge. In all, there were 59 documented rock falls in 2010, with anapproximate cumulative volume of 2,900 cubic meters (8,500 tons), more thanhalf of which derives from the El Capitan rock falls. For comparison, thecumulative volume for 2009 was roughly 17 times greater, at about 48,120cubic meters (142,000 tons); in that year the large volume was dominated bythe March 2009 Ahwiyah Point rock fall. Small rock falls are much morelikely to occur than large rock falls, but large rock falls represent a farmore important source of rock fall debris. The database of rock falls andother geologic events in Yosemite, begun in 1857, now documents over 740events, making it one of the longest and most detailed landslide databasesin the world.

It is very likely that there were additional rockfalls in 2010, but theseevents either were not witnessed or went unreported. If you witness arockfall of any size, encounter fresh rock debris, or hear cracking orpopping sounds emanating from the cliffs, please contact park geologistGreg Stock at (209) 379-1420, or at greg_stock@nps.gov, or contact ParkDispatch. Predicting rock falls is not yet possible, but understanding theevents that do happen is an important step toward this goal. For moreinformation on rock falls and rock fall research in Yosemite, please seethe Park’s web page: http://www.nps.gov/yose/naturescience/rockfall.htm

Monday, January 10, 2011

Check out this incredible video of flash flooding in Queensland, which came to my attention courtesy of Yorrike on Twitter. A couple of thoughts on the event: As I watched, I thought "why aren't these people moving their cars out of the way?". Of course, hindsight is wonderful, and one can't know how bad the flood is going to be until one's car is floating away. Then again, midway through the video, a fellow is seen moving his car, and I suddenly realized how unwise that could have been, given how easily the other cars floated away.

On a sedimentary note, at the end the cars display imbrication, which is something pebbles do in a stream that allows us to see which way water was flowing (a paleocurrent indicator). I can't tell if the cars are oriented correctly, but the similarity to the cobbles below is striking. This picture is from Andrew Alden's About Geology Page, and this link is a good place to find out about imbrication.

Postscript:The person who posted this video notes the following on his Youtube page:With the incredible exposure that my video is receiving all over the internet and media worldwide I would like to encourage you to donate to the relief appeals.

Thursday, January 6, 2011

It was a gloomy day Wednesday in the fog of the valley, and a beautiful sunny day in Yosemite Valley. I gathered a few more pictures from the day to add to yesterday's collection. I have lots of pictures from many trips to Yosemite, but I don't think I've ever been there when there was so much snow and ice. Above is Sentinel Dome, one of the slightly lesser known icons of the valley, a cliff that would be a more famous landmark if there weren't Yosemite Falls on the opposite side of the valley to distract everyone.

Half Dome is pretty much the most famous rock in Yosemite Valley. When one rounds the corner on the road from Crane Flat, El Capitan and Half Dome make a memorable debut (enhanced a bit here with the zoom lens). Ice has a hard time sticking to the face of El Cap and Half Dome, but the snow nicely coats the summit.

Hmm...I don't think anyone has ever thought to take a picture of Half Dome from this angle...from the middle of the parking lot at Curry Village. I've taken this picture about a hundred times, maybe more, but again rarely with so much snow. There is a single telephone wire that gets in the way of pictures in the parking lot. One has to shift around a bit to make sure it doesn't show up in the image.

The Cathedral Rocks take on a whole different aspect in the late afternoon shadows. Mist rises from the meadows as the temperature quickly drops.

Pools of melted snow reflect the high cliffs above...

Turtleback Dome is usually visible from the Crane Flat road, but it can sometimes be a little hard to see the glacial erratics scattered across the summit of the dome. Erratics are boulders left behind during the one of the early glacial episodes that filled Yosemite to the brim. The snow highlighted the boulders yesterday (below).

Wednesday, January 5, 2011

As I noted in this morning's post, I needed to decide whether to be fully prepared for the new semester, or be irresponsible and let a few prep items wait until the weekend. Logic won out, so we headed up the road to get out of the fog for a few hours and see what winter in Yosemite could provide us. What a day!

Have I ever mentioned that I drive a Subaru? With the all-wheel drive that I am really happy with? I passed everyone putting on their snow chains and took the Big Oak Flat Entrance road to Crane Flat, which at 6,200 feet was beneath several feet of fresh new snow. The trees were weighted down, and there was a constant rain of snow chunks off the branches and onto the ground (and cars) below. My car didn't crash into anything or spin out (possibly because I was going about 12 mph...). That's one of the nice things about California: we get to visit the snow if we want to, but we don't have to live in it unless we want to. So many of the usual wonderful sights in Yosemite Valley take on a completely different aspect under a mantle of snow and ice. Bridalveil Fall (above) and Cloud's Rest were coated with ice, looking most unlike their summer selves. The furrows on the northern slope of Cloud's Rest are avalanche chutes, and several fresh slides can be seen in the photo (click on the photo to enlarge and check below the two barren spots).

Upper Yosemite Fall had a special treat for us, an afternoon rainbow...

One of the most beautiful trees in the world had barren snow-covered branches, and a few broken ones, but it will be back in the spring. I'll have to take a closer look on a warmer day; I always assumed it was an oak of some kind, but I've heard it called an elm tree (I'm open to corrections, I'm a geologist, not a botanist!).

The snowdrifts melt into ponds in places that are normally meadows during warmer seasons. The Cathedral Rocks were nicely reflected on the water in the meadow below.

The days are certainly shorter, and our few hours were used up quickly. We needed to leave before the ice on the roads froze, but we couldn't resist the sunset, so we stopped at Valley View and enjoyed the late afternoon sunshine on the granite cliffs....

...and the rising mist on the Bridalveil Meadow, with the face of El Capitan in the distance. Funny how someone's like or dislike of fog can be highly dependent on the setting in which it occurs...

The last gift of our journey was one of the locals hanging out along the highway near the park exit. I know the coyote looks like he is thinking deep carnivorous philosophy, but he was mostly asking for a handout. We waved and moved on, back down the hill into the valley fog and darkness. Our national parks are precious places.

The Tule Fogs have arrived with a vengeance in California's Great Valley (Central Valley). After a series of very wet storms over the last few weeks the ground is saturated with water, but the storms are done with for the moment. This is a relief for anyone in the path of mudflows and flooding, but the stagnant air in the valley results in a temperature inversion with cold dense air below, and relatively drier air at higher levels. As the ground loses heat by infrared radiation, water vapor reaches the dew point and clouds form at ground level. The fog can be dangerously thick, with visibility measured in tens of feet sometimes. Driving in the fog is not unlike driving with cotton balls stuffed behind your sunglasses, and we have had some legendary chain reaction accidents involving dozens of cars on Highway 99 and Interstate 5.

I don't like the fogs very much. I don't like driving in them, and I hate that I am wandering about in the gloom, knowing that the sun is shining brightly just a few hundred feet over my head. School starts on Monday, so I should be getting everything ready; the syllabi are in fact done, and I spent a few hours cleaning up the lab yesterday. I'm kind of ready; there is a lot more I could be doing...but...I chanced on the webcam of the Yosemite Conservancy this morning, and...well...I'll see you all later, I've got one more field excursion to make before the semester starts!

Monday, January 3, 2011

It's been nearly a year since Art Clokey, the creator of Gumby and Pokey, passed away at the age of 88. I watched Gumby as a child, although it's been a long time and I don't remember a lot aside from the strange way Gumby skated, and that his friend was the orange horse named Pokey. They helped kids solve moral quandaries. Many people today probably remember Gumby more from the Saturday Night Live sketches in the 1980's with Eddie Murphy. I didn't know a lot about about Art Clokey himself until this year, when I found that he had a profound interest in geology! He attended geology classes at my alma mater, Pomona College, although the second world war prevented him from finishing a degree. He was the adopted son of a professor at Pomona College as well. It is a small world sometimes.

My intention was to talk about lighter things, though. These are the characters that grace the top of the chalkboard in my geology laboratory. I use them to illustrate a number of geological principles, including the difference between right and left lateral offsets on a strike-slip fault. Note, for instance, how in the picture below that from Gumby's point of view, Pokey has moved to Gumby's right. Putting yourself in Pokey's place, you can see how Gumby has moved to Pokey's right. This fault moved with right lateral motion.

I also describe Gumby in a perilous situation below, where he is about to be squashed in a fault zone (Maybe we need Mr. Bill for this one....). He has to climb out, but he can only step on the fault's footwall. The overhanging block, the one on which he would bump his head, is the headwall. When faults move vertically, they will be defined as normal or reverse based on the relative movement of the headwall relative to the footwall (headwall up is reverse; headwall down is normal).

There are mineralogical connections as well. Gumby is a tenacious character sometimes, so helps to demonstrate the mineral property of tenacity, that is the physical reaction a mineral has to stress such as crushing, bending, or breaking. Many minerals are brittle, meaning they snap and break in response to stress without significant bending. Other minerals, like thin sheets of mica, are elastic, meaning they bend under stress, but return to their original shape. Gumby, on the other hand, personifies flexible tenacity. He bends, and stays bent. Minerals like gypsum or chlorite may display this property.

There's a mystery this year in the lab. You may have noticed in the second photo that there is a little Gumby and Pokey, and a big Pokey, but no big Gumby. Gumby has disappeared. You would think that in a geology lab that shiny sparkling crystals and fossil samples would be more highly favored items for those with sticky fingers. Who knows what darkness lies in the hearts of humans?

There is actually an entire menagerie of prehistoric creatures inhabiting the top of the chalkboard (below). They serve various purposes, mostly to show all the mistakes that toymakers make when they produce toy "dinosaurs". I do actually find myself wondering if there is some sort of "Toy Story" drama taking place up there, and that Gumby has disappeared into a claymation alternate Universe to solve some awful problem somewhere. O, Gumby, where art thou? I hope he comes back.

About Me

I am a teacher of geology at Modesto Junior College and former president of the National Association of Geoscience Teachers, Far Western Section. I have led field trips all over the western United States, and a few excursions overseas, but my homebase is the Sierra Nevada, the Great Valley, and the Coast Ranges of California.

Ask Geotripper

Is there something about geology that you are curious about? Do you have questions about the scientific aspects of political controversies? I can try to provide a scientist's perspective. Your questions and possible answers could be a springboard to a blog discussion, or they can be private. Anonymity is always assumed. Contact Geotripper at hayesg (at) mjc.edu.

Blooks, Boogers and Bleries

Here are some of the series I've produced for the Geotripper Blog:

The Other California: what to see when you've seen all the really famous places in the Golden State (in progress).Into the Great Unknown: A rafting journey down the Colorado River through the Grand Canyon. The most incredible adventure of my life (so far)!

The Hawai'i That Was: An exploration of the geology, natural history, and anthropology of the most isolated lands on the planet. It's a lot more than beaches, shopping, and palm trees!